An unusual form of constrictive pericarditis : Annular constriction
Posted Apr 22 2010 7:24am
Constrictive pericarditis(CP) has been a fascinating disease for the cardiologists for many decades . (Of course , not so fascinating for our patients!) The reason why clinicians were thrilled to diagnose this entity is due to the unique clinical and echocardiographic and hemodynamic features. Further , it is one of the few curable forms of cardiac failure.
It is also about the philosophy , pericardium an inert membrane which is supposed to protect the heart , becomes a villain . When this innocuous layer is insulted by chronic infection (Tuberculosis most common) , radiation injury or post cardiac surgery it takes a dangerous avatar and start invading the organ which it guards .
The pericardium becomes thickened , (often > 5mm -2cm) calcified , behaves like a “shell of tortoise ‘ and begin to constrict the heart . Once the process of constriction sets in it becomes relentless . It only requires , a 10 -15mmhg of constrictive pressure to make the poor heart struggle to relax .(The maximum intracardiac diastolic pressure ,12mmhg(LV) .For the right side of the heart it is very low (0-5mmhg) .
So it is obvious the right side of the heart RA, RV gets compressed first .This is why the classical features of constriction with edema , ascites elevated JVP occur.The associated hepatomegaly some times mimic a chronic liver disease. Of course relying only on the classical findings to diagnose CP would be a crime now .
There are many atypical varieties of CP
* Rarely constriction is confined to AV groove . This article is about this entity.
It is difficult to imagine how a pericardium constrict a rigid fibrous skeleton of the heart namely the AV groove.
But what happens is , there are some gaps in the ring . The posterior mitral annulus which has a deficient rim and forms the most vulnerable zone for pericardial constriction
Further , AV groove is located in a relatively gravity dependant portion of the heart . It facilitates stasis of inflammatory exudate in this groove .This may be the reason why the AV groove shows high incidence of calcification.
Clinical features of AV groove constriction
It mimics a presentation of valvular heart disease.
A mid diastolic murmur across mitral valve may occur mimicking valvular MS.
Synonym : Mounsey’s pericarditis
This type of pericarditis should ideally be called as Mounsey’s constrictive pericarditis for his
elegant description of this entity 5o yearts ago even before Echocardiography was invented.
(These are the days , we struggle to diagnose Mitral stenosis without echo is a different story !)